Increasing membrane protection in Lactobacillus plantarum cells overproducing small heat shock proteins

A potential link between small heat shock proteins (sHsps) and membranes in Lactobacillus plantarum WCFS1, was investigated. The sHsps family is the best characterized protein subset among of L. plantarum Hsps, and it represents the principal heat shock regulon of Gram positive bacteria recognized in this bacterium. We found that the exposure to benzylic alcohol (60 mM), that causes only a membrane fluidization without any other stress, can induce transcription of the shs genes to the same extent as a lethal heat shock. Using a fluorescence anisotropy-based method, we detected a reduction of the maximal fluidification level in two L. plantarum strains that singly over-produce Hsp18.5 and Hsp19.3. Overall, these results indicate, under the stress conditions analysed, a membrane-activity effect of two members of sHsps family of L. plantarum WCFS1. Furthermore, these evidences represent the basis to propose membrane fluidity as a new target for pre-stress treatments to enhance probiotic, food starter, and bioproduction applications of L. plantarum.